[PATCH v2 43/52] powerpc/64s/exception: machine check early only runs in HV mode

[Mahesh J Salgaonkar]

On 2019-06-20 15:14:50 Thu, Nicholas Piggin wrote:
> machine_check_common_early and machine_check_handle_early only run in
> HVMODE. Remove dead code.

That's not true. For pseries guest with FWNMI enabled hypervisor,
machine_check_common_early gets called in non-HV mode as well.

   machine_check_fwnmi
     machine_check_common_early
       machine_check_handle_early
         machine_check_early
           pseries_machine_check_realmode

Thanks,
-Mahesh.

> 
> Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
> ---
>  arch/powerpc/kernel/exceptions-64s.S | 38 +++++-----------------------
>  1 file changed, 6 insertions(+), 32 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
> index b12755a4f884..f3362adc99e6 100644
> --- a/arch/powerpc/kernel/exceptions-64s.S
> +++ b/arch/powerpc/kernel/exceptions-64s.S
> @@ -1014,10 +1014,7 @@ TRAMP_REAL_BEGIN(machine_check_common_early)
>  	/* Save r9 through r13 from EXMC save area to stack frame. */
>  	EXCEPTION_PROLOG_COMMON_2(PACA_EXMC)
>  	mfmsr	r11			/* get MSR value */
> -BEGIN_FTR_SECTION
> -	ori	r11,r11,MSR_ME		/* turn on ME bit */
> -END_FTR_SECTION_IFSET(CPU_FTR_HVMODE)
> -	ori	r11,r11,MSR_RI		/* turn on RI bit */
> +	ori	r11,r11,MSR_ME|MSR_RI	/* turn on ME, RI */
>  	LOAD_HANDLER(r12, machine_check_handle_early)
>  1:	mtspr	SPRN_SRR0,r12
>  	mtspr	SPRN_SRR1,r11
> @@ -1124,11 +1121,8 @@ EXC_COMMON_BEGIN(machine_check_handle_early)
>  	bl	machine_check_early
>  	std	r3,RESULT(r1)	/* Save result */
>  	ld	r12,_MSR(r1)
> -BEGIN_FTR_SECTION
> -	b	4f
> -END_FTR_SECTION_IFCLR(CPU_FTR_HVMODE)
> 
> -#ifdef	CONFIG_PPC_P7_NAP
> +#ifdef CONFIG_PPC_P7_NAP
>  	/*
>  	 * Check if thread was in power saving mode. We come here when any
>  	 * of the following is true:
> @@ -1141,7 +1135,7 @@ END_FTR_SECTION_IFCLR(CPU_FTR_HVMODE)
>  BEGIN_FTR_SECTION
>  	rlwinm.	r11,r12,47-31,30,31
>  	bne	machine_check_idle_common
> -END_FTR_SECTION_IFSET(CPU_FTR_HVMODE | CPU_FTR_ARCH_206)
> +END_FTR_SECTION_IFSET(CPU_FTR_ARCH_206)
>  #endif
> 
>  	/*
> @@ -1150,12 +1144,11 @@ END_FTR_SECTION_IFSET(CPU_FTR_HVMODE | CPU_FTR_ARCH_206)
>  	 */
>  	rldicl.	r11,r12,4,63		/* See if MC hit while in HV mode. */
>  	beq	5f
> -4:	andi.	r11,r12,MSR_PR		/* See if coming from user. */
> +	andi.	r11,r12,MSR_PR		/* See if coming from user. */
>  	bne	9f			/* continue in V mode if we are. */
> 
>  5:
>  #ifdef CONFIG_KVM_BOOK3S_64_HANDLER
> -BEGIN_FTR_SECTION
>  	/*
>  	 * We are coming from kernel context. Check if we are coming from
>  	 * guest. if yes, then we can continue. We will fall through
> @@ -1164,7 +1157,6 @@ BEGIN_FTR_SECTION
>  	lbz	r11,HSTATE_IN_GUEST(r13)
>  	cmpwi	r11,0			/* Check if coming from guest */
>  	bne	9f			/* continue if we are. */
> -END_FTR_SECTION_IFSET(CPU_FTR_HVMODE)
>  #endif
>  	/*
>  	 * At this point we are not sure about what context we come from.
> @@ -1199,7 +1191,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_HVMODE)
>  	cmpdi	r3,0		/* see if we handled MCE successfully */
> 
>  	beq	1b		/* if !handled then panic */
> -BEGIN_FTR_SECTION
> +
>  	/*
>  	 * Return from MC interrupt.
>  	 * Queue up the MCE event so that we can log it later, while
> @@ -1208,18 +1200,7 @@ BEGIN_FTR_SECTION
>  	bl	machine_check_queue_event
>  	MACHINE_CHECK_HANDLER_WINDUP
>  	RFI_TO_USER_OR_KERNEL
> -FTR_SECTION_ELSE
> -	/*
> -	 * pSeries: Return from MC interrupt. Before that stay on emergency
> -	 * stack and call machine_check_exception to log the MCE event.
> -	 */
> -	LOAD_HANDLER(r10,mce_return)
> -	mtspr	SPRN_SRR0,r10
> -	ld	r10,PACAKMSR(r13)
> -	mtspr	SPRN_SRR1,r10
> -	RFI_TO_KERNEL
> -	b	.
> -ALT_FTR_SECTION_END_IFSET(CPU_FTR_HVMODE)
> +
>  9:
>  	/* Deliver the machine check to host kernel in V mode. */
>  	MACHINE_CHECK_HANDLER_WINDUP
> @@ -1238,13 +1219,6 @@ EXC_COMMON_BEGIN(unrecover_mce)
>  	bl	unrecoverable_exception
>  	b	1b
> 
> -EXC_COMMON_BEGIN(mce_return)
> -	/* Invoke machine_check_exception to print MCE event and return. */
> -	addi	r3,r1,STACK_FRAME_OVERHEAD
> -	bl	machine_check_exception
> -	MACHINE_CHECK_HANDLER_WINDUP
> -	RFI_TO_KERNEL
> -	b	.
> 
>  EXC_REAL_BEGIN(data_access, 0x300, 0x80)
>  	EXCEPTION_PROLOG_0 PACA_EXGEN
> -- 
> 2.20.1
> 

-- 
Mahesh J Salgaonkar